1. Field of the Invention
The present invention relates to an image processing apparatus and, more particularly, to an image processing apparatus for performing an image editing process to cut out a part of an image or to synthesize a plurality of images.
2. Related Background Art
In general, when an image editing and the like are performed in such a kind of apparatus, a case where a part of the image data is masked and cut out and the cut-out image is output to a display frequently occurs.
In such a case, a cut-out shape is not limited to an area which is surrounded by geometrical line segments such as simple square, rectangle, regular polygon, or the like but it is desirable that an image can be cut out by a curved area. As a method of cutting out an image in a curved area, there has conventionally frequently been used a method whereby a bit map memory which is used only to cut out (mask) an image is prepared and it is decided on the basis of the bit data in the memory whether the data is cut out or abandoned.
For example, in the case of masking the image data on the basis of the data from the masking bit map memory, only the data in a desired area is extracted from a single image and the resultant data is written into a memory on the destination side.
The applicant of the present application has already proposed such a mask processing method in 07/40895 filed on Sept. 18, 1989 which is a continuation of U.S. patent application No. 886,222 filed on July 16, 1986 now abandoned and 07/506550 filed Apr. 6, 1990 which is a continuation of U.S. patent application No. 940,395 filed on Dec. 11, 1986 now abandoned.
On the other hand, hitherto, to synthesize images stored in two memories, there has been used a method whereby only the image in the necessary portion in the image to be synthesized is cut out and synthesized to another image.
In this case, as shown in FIG. 24, an example in which the portion of the image surrounded by a broken line is synthesized to a ground image to thereby produce a synthesized image can be mentioned. As a practical processing procedure, the image in the portion surrounded by a broken line is synthesized to the ground image on the basis of the position information at points A, B, and the like which indicate the area (hereinafter, referred to as a mask) to cut out the image to be synthesized.
However, although no problem occurs in the case where the shape of the mask is square or rectangular as in the foregoing example, as the shape of mask becomes complicated, an amount of position data to indicate the shape of the mask increases and in order to perform the processes between two memory frames by a CPU or the like, its algorithm becomes extremely complicated.
On the other hand, there is considered a method whereby an image is divided into a plurality of images within a range which can be displayed and these images are synthesized by the foregoing method. But, this method is attained by the inconvenience that the operator cannot know the whole image.
In addition, since the printing output accuracy must be made high and the mask shape must be also made smooth, the capacity of the image memory and the capacity of the mask memory also increases extremely. Thus, there is a drawback that the cost and size of the system increase.
Further, since the resolution of the display is obviously lower than that of the printer output, it is also necessary to match the image memory with the display apparatus and printer.